1. Field of the Invention
The present invention relates to a device for selecting and conveying printing plates which accommodates plural types of printing plates in cassettes exclusively used for the respective types of printing plates, and arbitrarily selects a printing plate from the plural cassettes, and conveys the printing plate to a subsequent process.
2. Description of the Related Art
Techniques (printing plate exposure devices) have been developed which, by utilizing a printing plate in which a photosensitive layer is provided on a support, record an image directly onto the photosensitive layer (emulsion surface) of the printing plate by a laser beam or the like. With such a technique, it is possible to quickly record an image onto a printing plate.
Cassettes, which accommodate plural printing plates which are stacked one on another, are loaded in an automatic printing plate exposure device which uses the technique of recording images onto printing plates. The printing plates are removed one-by-one from the cassettes, and are fed into an exposure section.
The cassette is loaded substantially parallel to the surface on which the device is set. A plurality of printing plates are stacked on a stacking base of the cassette.
In this state, in order to remove the uppermost printing plate, usually, the printing plate is suctioned by suction cups. The suction cups which are suctioning the printing plate are guided along guide rails or the like and fed into the exposure section which is the subsequent process.
There are plural types of printing plates having different sizes, materials, and the like. Usually, each cassette accommodates a single, different type of printing plate, and plural cassettes are usually stored in a separate place from the device. A needed cassette is loaded into the device, and the aforementioned operation of removing the printing plate from the cassette is carried out.
However, there are cases in which a single device requires plural types of printing plates randomly, and processes these plural types of printing plates. In such cases, the work of replacing a cassette must be carried out each time a different type of printing plate is to be exposed. The work is complex and work efficiency markedly deteriorates.
Thus, conventionally, a plurality of cassettes are disposed in advance within the device. When a printing plate of a specific type is needed, the corresponding cassette is moved to a predetermined position, and a printing plate is removed from that cassette which has been moved to the predetermined position.
In this case, a so-called batch system is used in which, when the removal of a printing plate from one cassette has been completed, that cassette must be returned to its original position. Thus, this system is not advantageous from the standpoint of efficiency.
In order to overcome this drawback, a method has been proposed in which a plate removing device is moved to the respective cassettes, without the cassettes being moved within the device. In this way, the cassettes do not move, and work efficiency can be improved.
However, the plate removing device must be moved each time to a position corresponding to a position of a different cassette. Further, space must be provided for the plate removal operation at the respective positions corresponding to the plural cassettes. Thus, even more space is required for placement of the entire device.
In view of the aforementioned, an object of the present invention is to provide a device for selecting and conveying printing plates which eliminates the complexities involved in the work of so-called batch processing, and which, by realizing, in a small space, the operation of removing printing plates from cassettes, can save on space and improve work efficiency.
In order to achieve the above object, in accordance with a first aspect of the present invention, there is provided a device for selecting and conveying printing plates, comprising: a plurality of cassettes each able to accommodate a plurality of printing plates in a state in which the printing plates are stacked substantially horizontally, the plurality of cassettes being respectively movable, independently from others of the plurality of cassettes, between removal positions and withdrawn positions which are set apart from the removal positions substantially in a horizontal direction; and a conveying unit able to access each cassette of the plurality of cassettes in order to remove a printing plate from a cassette positioned at the removal position, wherein all of the cassettes are aligned in a row vertically beneath the conveying unit when the cassettes are positioned at the removal positions.